California has 7.88 gun deaths per 100,000 people, the report found. Hawaii's rate was 3.31, and Alaska's was 20.28, the report found.

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None of the major pro-gun organizations would comment on the report, according to the San Francisco Chronicle.

2012 was one of the deadliest in the nation's history for mass shootings. Before a gunman in Newtown, Conn., murdered 26 people, including 20 children, a shooter at a Colorado movie theater killed 12, and a gunman at Oikos University in Oakland killed seven people.

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All guns were acquired legally.

The weapon used in the elementary school massacre, the military-style Bushmaster, is banned in California but can be imported -- from Nevada, the newspaper reported.

The nation had an assault weapon ban in place from 1994 to 2004, legislation passed following the 101 California Street massacre in San Francisco, when a gunman toting assault weapons killed eight people.

In California, a background check is required before any firearm sale, and only one handgun can be purchased per month.